View Full Version : 95 Impreza 1.8 knock

11-27-2009, 03:26 PM
my 95 impreza 1.8L has a knock when i first start it up after its been sitting awhile. it only knocks for a second then goes away. i can rev the heck out of it after and it doesnt knock. motor runs perfect otherwise. though i would post to see if anyone had any ideas what would cause this, or maybe its a common issue with these motors. thanks for the help

12-01-2009, 12:24 AM
The most common problem is piston slap. When the motor is cold you have the most clearance between the piston skirt and cylinder wall. After the engine gets a little heat into the piston it grows and takes up the slap. This however is the effect of either high mileage, or overheating. This noise is not going to destroy your motor, but it will shorten the life of the engine. If you have caught it soon enough you could have a new set of pistons put in or if the clearance is not to great have the pistons coated with moly graphite coating to take up some clearance. NOTE it is very hard to diagnose a noise without hearing it but this will give you a place to start. If you have any other questions please feel free to call and we can go over some other things it could be and some solutions.